1. Field of the Invention
The present invention relates to a security document, in particular a security paper, bank-note, identification card, etc., having a feature which is embedded, for example in the form of a safety thread, in the interior of the document and capable of being tested mechanically in order to recognize the authenticity of the document.
2. Description of Related Art
It is known to protect security papers and other moneyvalue products made of paper or synthetic material against unauthorized imitation by embedding so-called safety threads therein. These safety threads generally consist of narrow strips of a synthetic or metal film, textile threads, wires and similar materials.
It is also known (e.g. German Offenlegungsschrift No. 14 46 851) to equip safety threads additionally with special properties by printing very fine letters (so-called micro-letters which are approx. 0.4 mm high) on them, for example, which make it especially difficult for a forger to imitate them. Coatings made of colored materials across the surface are also known in this connection.
In the course of the increasing automation, there have also been efforts to design the safety threads in such a way that they are suitable for mechanical testing. Thus, safety threads are provided, for example, with substances which fluoresce under UV light or have magnetic or special properties detectable using X-rays (see German Offenlegungsschrift No. 27 54 267, for example). The embedding of such threads in bank-notes or other security documents then offers the possibility of ascertaining the authenticity or the value of a document using appropriate testing devices.
The mechanical testing of security documents such as identification cards, bank-notes, etc., is desirable nowadays above all for money-issuing machines, so-called POS terminals or at bank counters. Rapid and mechanical testing of documents, for example with respect to their authenticity or their value, is also particularly useful and helpful, however, for the automatic sorting or processing of bank-notes or similar money-value products.